Trucks and trailers loaded with cargo and products move across the country to deliver products to commercial loading and unloading docks at stores, warehouses, and distribution centers. Trucks can have a trailer mounted on the truck, or can be of a tractor-semi trailer configuration. To lower overhead costs at retail stores, in-store product counts have been reduced, and products-in-transit now count as part of available store stock. Unloading trucks quickly at the unloading docks of warehouses and regional distribution centers has attained new prominence as a way to refill depleted stock.
Trucks are typically loaded and unloaded with forklifts if the loads are palletized and with manual labor if the products are stacked within the trucks. Unloading large truck shipments manually with human laborers can be physically difficult, and can be costly due to the time and labor involved. In addition, hot or cold conditions within a confined space of a truck trailer or shipping container can be deemed unpleasant work. Consequently, a need exists for an improved unloading system that can unload bulk quantities of stacked cases and cargo from truck trailers more quickly than human laborers and at a reduced cost.
In order to be economical, automation of loading or unloading needs to be relatively fast. Generally-known approaches to unloading cartons quickly have had extremely limited acceptance. Each carton is generally conveyed rearward in a singulated fashion, limiting the rate at which cartons can be unloaded. Some prototype truck unloaders have attempted to increase the throughput, and thus improve their return on investment (ROI) by placing more than one carton on a time on a laterally-moving conveyor surface diverts onto a rearward longitudinally-moving conveyor surface.